108 PHYSIOLOGICAL KEGULATIONS 



be estimated by indirect means, as follows. The mean rate of total 

 water ingestion is about 0.26% of Bo/bonr, as compared with the 

 rate in other climates of 0.13. On the equilibration diagram (fig. 

 61) this rate is found at a load of -0.2% of Bq, hence it is the 

 approximate deficit. It is not outside the usual variation of con- 

 tents found in 24-hour periods in other climates (table 15) nor out- 

 side the standard of variation found in that climate. 



In the various states considered above, the content at balance 

 (Wo) is believed to be approximately constant. Shifts in the posi- 

 tion of Wo have been partially investigated in man, particularly in 

 pathological conditions. Examples of such shifts (water reten- 

 tion) are found in lobar pneumonia (Sunderman and Austin, '30), 

 and in treatment with the drug phenylethyl hydantoin (Rockwell, 

 '35). After apparently remaining at the new Wo for several days, 

 the body reverts (at crisis) to the original Wo- 



<^ 35. Summary 



Investigations of water balance in man are slightly more lim- 

 ited than in the dog, for in man responses in stationary state of 

 water deficit are unknown. Quantitative correlations in the other 

 states of water content are drawn. The same velocity quotients 

 prevail, in the hours after the first, following a single ingestion 

 of water, and after 8 to 16 rapidly repeated ingestions. Several 

 means of testing and characterizing water relations are empha- 

 sized : time relations, completeness of return, and maximal rates of 

 exchange. 



Man uses all four of the possible means of recovering the usual 

 water content, as does the dog. In deficits, gains are increased 

 while losses are decreased slightly, thus sparing water ; in excesses, 

 losses are increased and gains are decreased to the minimum of 

 oxidative formation of water. These four modifications of activi- 

 ties appear to constitute the armamentarium for any adjustment 

 of water content. 



Rates of loss are slightly smaller per unit of body weight in 

 man than in dog. In man the rates are less nearly proportional 

 to water load, tending to prolong the life of larger loads. 



The most remarkable feature of recovery in man is the slow 

 rate of ingestion after any deficit of water. Often it is asked, why 

 is the drinking leisurely? No other peculiarity of metabolism or 

 structure appears to be known that is especially related to this one. 



